1. Field of the Invention
This invention relates to a magnetic recording apparatus in a still camera in which a magnetic head for magnetic recording is urged against a magnetic recording medium having various kinds of photographing information such as exposure condition, etc. formed on the surface of film by a magnetic material when the film is moved, thereby magnetically recording the information. The invention relates more particularly to a driving mechanism for controlling the magnetic head so as to hold the magnetic head in a position retracted from the surface of the film during ordinary one-frame photographing and to maintain the magnetic head urged against the surface of the film during continuous photographing (continuous shot) in which a plurality of frames are continuously photographed.
2. Related Background Art
In 8 mm cinecameras or the like, it is common to magnetically record ambient sounds or the like during photographing. In such a cinecamera, for the reason that photographed images are moving images and for reasons relating to construction, such as the arranging of an image photographing portion corresponding to a photographing optical system and a sound recording portion, the image recording portion on the film and the sound recording portion corresponding to the image are spaced apart from each other in the direction of movement of the film. Accordingly, in the cinecamera, it is possible to consider the image recording on a film screen and the magnetic recording entirely independently of each other. Therefore disposition, construction, etc. of each portion is relatively simple and concern for the mutual interference between the two mechanism portions is entirely unnecessary. Stable image photographing and sound recording on the film can thus readily be accomplished.
The application of such a technique of magnetically recording information on film to a still camera or the like is also conceivable. In such case, the information to be recorded may include photographing information such as exposure and aperture during photographing, film speed condition, date and time of photographing or trimming information. If these bits of information are recorded on the surface of film during photographing, the exposure condition, etc. during printing can be set in conformity with the conditions during photographing by the information being read in the processing laboratory or the like, thereby improving the printed photographs. The photographing process may also be enhanced. For example, it would become possible to effect photographing on the premise that a portion of the screen is enlarged in advance, thereby obtaining such printed photographs as taken by the use of a telephoto lens even if the focal length of the photo-taking lens of the camera is limited.
In the case of a still camera, however, there are significant constraints which are not present in the case of a cinecamera. For example, there is little room for spacing of the photographing portion and the magnetic recording portion from each other. In addition, it is common to cut the film into suitable lengths as negatives. Both of the foregoing factors might suggest locating the magnetic head in a portion approximate to a film passageway which faces the aperture of the camera body in order to record information on or near the marginal side edge portion of the film as close as possible to the photographing screen. Such an arrangement, however, would lead to a further problem which notably does not arise in the cinecamera. In particular, the pressure contact force of the magnetic head against the film surface during photographing could cause bending or twisting of the film, resulting in reduced planarity of the film surface and consequent deviation of the focusing position relative to the surface.
Still cameras capable of magnetically recording information on a film have been proposed in the prior art. However, there remains a need for a camera which achieves a compact construction and which offers excellent performance despite the aforementioned constraints. For example, U.S. Pat. No. 4,860,037 discloses a magnetic recording type still camera system. However, in this system, a magnetic head records data on but a small area of a film leader and the head is always urged against the film surface, with possible adverse effects on the planarity of the film.